High-precision analysis is demanded of sample analyzers. For example, Japanese Laid-Open Patent Publication No. 4-84770 discloses an electrolyte measuring apparatus for improving analysis accuracy. This electrolyte measuring apparatus improves analysis accuracy by repeating measurements until the difference in the measurement values of two consecutive measurements are within a set value range.
Automatic multifunction hemocyte analyzers are known (for example, model XE-2100 (Sysmex Corporation)) which automatically performs a PLT double count when the count value of blood platelets (PLT) is below a set value. In the PLT double count, PLT are counted using a double quantity of the sample used in a normal measurement. High precision analysis is therefore possible even when there is a low concentration of the substance being measured in the sample.
In the electrolyte measuring apparatus disclosed in Japanese Laid-Open Patent Publication No. 4-84770, however, high precision analysis results are difficult to obtain due to the wide variation in the measurement values of the individual measurements when there is a low concentration of the substance being measured in the sample.
In the automatic multifunction hemocyte analyzer above, a double quantity of reagent must be added to correspond to the double quantity of sample used in a normal measurement. Therefore a reagent mixing chamber which accommodates double the normal quantity of reagent, and a dosage pump which delivers double the normal quantity of reagent to the reagent mixing chamber are required, and result in increasing the overall size of the apparatus. Furthermore, although the amount of reagent used must be increased in order to perform high precision analysis even when the count value of the PLT in the sample is extremely low (for example, five times the normal quantity of reagent), there are limits to the increase in size of the reagent mixing chamber and dosage pump. It therefore can not be said that that measurement accuracy of this automatic multifunction hemocyte analyzer is adequate in the case of samples which have very low concentrations of a measurement substance.